Terne plate is a form of tinplate: a thin steel sheet coated with an alloy of lead and tin.
Terne plate was used for tinsmithed sheet metal goods, such as storage vessels, jugs and funnels, particularly for industrial use with flammable liquids.
Unlike tinplate, it was not used for long-term storage or around food items, owing to the high lead content.
[1][2] Today terne-coated metal is coated with 99.9% tin, instead of hot-dipping, a more consistent galvanic deposition process is applied.
It was one of the cheapest alloys suitable for this, and the tin content was kept at a minimum while still adhering to a hot-dipped iron sheet, to minimize the cost.